1. Field of the Invention
The present invention relates to a technique for measuring a distance to a detection target.
2. Description of Related Art
There is known a technique for calculating a distance to a detection target by emitting laser light and receiving the laser light reflected from the detection target. It is also known to adjust the level of such a reflected laser light being received to enable detecting a detection target with a high degree of accuracy.
For example, Japanese Patent Application Laid-open No. 2008-224239 describes changing the wavelength of a laser light being emitted to prevent the level of a reflected version of the laser light to be received through a bandpass filter from being saturated.
However, the technique described in this patent document has a problem that since feedback control of the temperature of a Peltier element has to be performed to change the wavelength of the laser light, a complicated structure is required. In addition, since feedback control involves a time delay, it is difficult to be used for automobiles.